Patent Document 1 (Japanese Patent Laid-open No. 2007-164356) co-assigned to the applicant, discloses a position indicator of an electromagnetic induction system. The position indicator of the electromagnetic induction system includes, at its position indicating part, a coil for indicating a coordinate position by electromagnetic induction with a tablet. The position indicator also includes an electric double layer capacitor that is used as a power supply. Patent Document 1 describes contactless charging by electromagnetic induction between the coil and a charger shaped in the form of a penholder. According to Patent Document 1, high-speed charging is performed when a user places the position indicator in the penholder, and thus the position indicator has superb operability which does not require the user to consciously perform charging operation.
In the case of the position indicator of the electromagnetic induction system of the type described above, a coordinate position is obtained by electromagnetic induction with the tablet. In general it is difficult to use the tablet sensor of the electromagnetic induction type also as a capacitive touch panel.
Patent Document 1 further discloses an example of a capacitive position indicator that can be used with a touch panel. Additional capacitive position indicators using a capacitive system are disclosed in Patent Document 2 (Japanese Patent Laid-open No. Hei 07-295722), Patent Document 3 (Japanese Patent Laid-open No. Hei 06-250772), etc.